The present invention relates to a three-pole, molded case circuit breaker of modular construction and compact physical size.
Heretofore, typical circuit protection for three phase electrical distribution circuits utilized in light industrial, commercial and institutional applications has been provided by three-pole molded case circuit breakers of the wire-in, wire-out variety. These circuit breakers would normally be installed in circuit breaker load centers containing banks of single-pole, plug-in circuit breakers for branch circuit protection. Since the typical three-pole circuit breaker, in addition to being nonplug-in, is wider than the combined width of three single-pole branch breakers, special provisions must be made to physically mount the three-pole breaker within the load center. Thus, the load centers must be specially designed to the customer's specifications to accept specified numbers of three-pole and single-pole breakers. Typically, the electrical connections between the three-pole breaker and the branch breaker line buses are pre-wired by the manufacturer. Under these circumstances, the load center is relatively inflexible in terms of the applications it can accommodate. That is, if the customer's electrical requirements should change in the future, the existing load center may not be conducive to the changed requirements. This is particularly true if an additional three-pole breaker is required.
It is accordingly an object of the present invention to provide a three-pole circuit breaker of compact modular construction.
A further object is to provide a three-pole circuit breaker of the above character which requires no special mounting provisions for its installation in a standard plug-in circuit breaker load center.
Another object is to provide a three-pole circuit breaker of the above character which is comparable in width to the combined widths of three, standard single-pole branch circuit breakers.
Yet another object is to provide a three-pole circuit breaker of the above character which is equipped with line terminal stabs enabling the installation of the breaker in any load center space normally occupied by three side-by-side branch circuit breakers.
A still further object is to provide a three-pole circuit breaker of the above character having improved current carrying and current interrupting capacities.
An additional object of the present invention is to provide a three-pole circuit breaker of the above character which is efficient in design, inexpensive to manufacture and reliable in operation.
Other objects of the invention will in part be obvious and in part appear hereinafter.